Electric switch



March 4, 1952 J. W. WooLF 2,587,948

ELECTRIC SWITCH Filed Aug. 30, 1949 2 SHEETS--SHEET l @YQVQYM March 4,1952 1 W, WOOLF 2,587,948

ELECTRIC SWITCH Filed Aug. 50, 1949 2 SHEETS-SHEET 2 72 50 JMP PatentedMar. 4, 1952 ELECTRIC SWITCH James W. Woolf, Franklin,

Manufacturing Company,

Pa., assigner to Joy Pittsburgh, Pa., a

corporation of Pennsylvania Application August 30, 1949, Serial No.113,154

f 11 Claims.

This invention relates to an electric switch, especially to a latch typereversing switch.

In mine haulage practice, it is common to use trolley shuttle cars in agreat many applications. Where such shuttle cars have to operate on agrade or slope, it is desirable to provide them with dynamic braking.When two cars have to pass on a hill or slope, the car going downhillmust get off the trolley in order that the car going uphill may continueunder power. With controlling circuits heretofore in use in shuttlecars, it has not been possible to provide dynamic braking during thetime that the shuttle car is oiT the trolley, because with the powerremoved the reversing switch contacts would drop out and interrupt thearmature circuit of the drive motors.

It is, accordingly, an object of this invention to provide a reversingswitch suitable for mine shuttle car applications which will not openits contacts upon failure of the power source for any reason. This andother objects are accomplished in a reversing switch having latch meansso arranged that the contacts are latched against opening and are openedwhen the latch is released upon operation of the switch to reverse thecontacts.

In the drawings:

Fig. l is a top plan view of a reversing switch made according to thisinvention.

Fig. 2 is a side elevation of the switch, with the mounting panel insection.

Fig. 3 is a view in section on line 3 3 of Fig. 2.

Fig. 4 is a view in section on line 4 4 of Fig. 2, but shown without themovable contacts.

Fig. 5 is a view in section on line 5-5 of Fig. 4; and

Fig. 6 is a partial View in side elevation, similar to Fig. 2, butshowing the contacts reversed from the position shown in Fig. 2.

' A mounting panel of any suitable non-conducting material is shown at2, and serves as a non-conducting member on which a nonmagnetic support4 is mounted by any suitable fastener means 6. The support 4 ispreferably an inverted U and may be provided with a stiftening member 8to brace the legs of the U.

A fixed electrical contact I, which may be referred to as a rst contact,is mounted on the non-conducting member 2 by any suitable means such asscrews I2. In a preferred form of the invention, the Xed or rst contactI0 takes the shape of a U, one leg of which is secured to the panel 2 asaforesaid, and provides a terminal to which a conductor I4 may besecured in good electrical contact relation. The actual fixed or firstcontact referred to thus constitutes the other leg of the U and isspaced a substantial distance from the panel 2. Preferably, there aretwo such contacts IIJ, as is best seen in Figs. l and 3.

Two magnetic base members I6 are provided, one for each of a pair ofelectromagnets I8 and 20. In a preferred form of the invention, magnetsI8 and 2D and magnetic base members I3 are secured to the support 4 byfastening means shown at 22. The fastening means 22 may consist ofthreaded members passing through openings in the base members I6 andthreadedly engaging cores 24 and 25 of magnets I8 and 20, respectively.The details of the engagement of cores 24 and 2S by screws 22 will bewell understood by those skilled in the art and need not be shown here.

An armature is provided for each magnet as shown at 28 and 30. Thesearmatures are pivotally mounted on the non-magnetic support 4 by meansof bolts 32 passing through and clamping bifurcated members 34 of thearmatures and passing freely through openings 36 in the non-magneticsupport 4. In a preferred form of the invention, the non-magneticsupport 4 is made of brass and the bolts 32 are made of iron or steel,whereby a good bearing is provided for the pivoting of the armatures 28and 30. A light spring 38 is provided to bias the armatures 28 and 30away from their respective magnet cores 24 and 28. Springs 38 arepreferably L-shaped, one leg of the L being placed against thenon-magnetic support and the other leg being clamped between a latchmember and the armature.

Each armature is thus provided with a latch member, armature 28 beingprovided with a latch member 40, and armature 38 having a latch member42. Suitable fastening means, such as screws 44, secure each latchmember to its armature.

A second armature is provided for each magnet, armature 46 being shownas associated with magnet I8 and armature 48 being shown as associatedwith magnet 23. The two armatures 45 and 48 are mounted for pivotalmovement on support 4 by means of bolts 5E?, in much the same manner asarmatures 28 and 38 are mounted by means of bolts 32. Movable contacts52 and 54 are mounted on armatures 46 and 4B, respectively. Inasmuch asContact I was referred to above as a first contact, contacts 52 and 54may be referred to as second and third contacts.

Although the details of mounting the second and third contacts 52 and 54do not per se form a part of this invention, it may be pointed outbriefly that the contacts 52 and 54 are carried on contact holders 56,which are pivotally mounted at 58 on brackets 60. Brackets 6D aremounted on transverse insulating blocks 64 and 66, which in turn aremounted on the armatures 46 and 45 respectively, Springs 68 are providedbetween one end of each contact holder 56 and its respective bracket 68to provide a yielding pressure or bias of the contacts 52 and 54 againstthe xed contact IU, or against a stop 68 when the movable contact is notengaging the fixed contact.

54. There are preferably twomovable contacts 52 and two movable contacts54, one on each side of the switch, for engagement with the two fixedcontacts I0. Correspondingly, there are two flexibleconductors and twoexible conductors 12, as may best be seen in Figs. 1, 3 and 4. Thetwoflexible conductors 10 engage terminals 14 and 1B, and the twoexibleconductors 12 engage terminals 18 and 88. The terminals aremounted on an insulating panel member 8|. In order to provide theconventional reversing-switch circuit, terminals 14 and 80 arecross-connected by a conductor strap 82, and terminals 16 and 18 arecross-connected by a conductor strap 84. The conductor strap 84 isinsulated in any suitable manner from the strap 82, as for example bymeans of a non-conducting sheath 86.

Latch members 48 and 42 were referred to above. A third latch member 81,consisting of a block 88 and side members 89, is supported by both ofthe armatures 46 and 48 by means of bolts 98. Thus, the latch member 81serves as a link connecting the two armatures 46 and 48. As

Flexible conductor 10 engages contact 52, and a similar flexibleconductor `12 engages contact 4 ture in its attracted position, the uxpath for armature 48 is through the upper end of armature 48, magneticbase member I6, magnet core 26 and part of armature 30. The air gap thenexists between the lower end of armature 48 and the left end of armature3E. Armature 48 is thereupon attracted toward armature 38, disengagingthe contacts I8 and 54. vInasmuch as latch member 81 serves as a linkconnecting the armatures 46 and 48, armature 46 is also moved Atowardthe right as seen in Fig. 2, causing engagement of contacts l0 and 52.With the parts in this position, latch member 40 is free to drop intothe recess .92, whereupon the parts take the position ,shown in Fig. 6and the contacts 52 and I8 are latched in engagement.

is best seen in Fig. 5, block 88 of latch member 81 is notched out toprovide recesses 92 and 94 for the engagement respectively of latchmembers 48 and 42. Thus, the latch members 48, 42 and 81 form latchmeans for holding the contacts in a selected engagement, as will be morefully brought out in the description of the operation.

Operation Let ,it be assumed that a shuttle car with a reversing switch,made according to the invention, is proceeding downhill with its switchparts occupying the relative positions shown in Fig. 2 and Fig. 5. Withthe switch parts as thus shown, latch member 42 engages recess 94, thuscooperating with the latch member 81 to hold it in its extreme leftwardposition and to keep the movablecontact 54 in engagement with fixedcontact l0. If then the shuttle car has to get off the trolley for anyreason, taking the electromagnet I8 oi the power source, contacts I8 and54 will, nevertheless, remain in engagement, because of the latch meansjust described. The armature circuits of the drive motors thus remainclosed and the vehicle continues to operate with dynamic braking.

Let it now be assumed that the vehicle is again on the trolley and thatit is desired to reverse the drive motors. The operator makes thenecessary manipulation of manually or pedally operated controls,whereupon electromagnet 28 is energized. The close proximity of thearmature 38 to the lower end of magnet core 26 makes it possible formagnet 20 to attract armature 38, pulling the lat-oh member 42 out citbe recess ,94. With ama-l The reverse of the operation, i. e., goingfrom the position shown in Fig. 6 to the position shown in Fig. 2, willbe readily understood by those skilled in the art from the abovedescription and need not be detailed here.

Ainong the advantages of a switch made according to this invention isthat vof maintaining the contacts in engagement, even after the systemis disconnected fromV the power source (or in case of a power failurefor any reason whatever), making it possible in the application of theinvention referred to herein to keep the shuttle car or other vehicleoperating with dynamic braking. Other advantages will be apparent tothose skilled in the art.

While there is in this application specically described one form whichthe invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration, and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

I claim:

l. In an electric switch, a first contact, a second contact and a Vthirdcontact, the contacts being mounted to provide relative movement of twoof them with respect to the other whereby said rst and second contactsare engaged to provide a desired electric circuit through the switch andalternatively said rst and third contacts are engaged to provide anotherdesired electric circuit through the switch, latch means for holding thecontacts in a selected engagement, the latch means including three`latch members, two electromagnets, a first armature for each of saidtwo magnets, one of the three latch members being supported by one rstarmature and another of the three latch members being supported by theother iirst armature, and a second armature for each of said twomagnets, the third latch member and the second and third contacts beingsupported by both of said second armatures.

2. A switch according to claim l, in which the flux path for each secondarmature includes vat least a portion of its associated rst armature.

3. In combination, a non-conducting member, an electrical contactmounted on the member, a non-magnetic support mounted on the member, apair of magnetic base members, a pair of electromagnets, means to secureeach electromagnet with one of said base members to the support, anarmature for each magnet, a second armature for each magnet, anelectrical contact mounted on each said second armature and movablethereby into engagement with the first-named electrical contact, a latchmember supported by both of the second armatures, and another latchmember on each rst-named armature and cooperable with the first-namedlatch member.

4. The combination of claim 3, in which the flux path for the secondarmature includes at least a portion of the rst armature.

5. The combination of claim 4, in which the first-named latch member isconnected to said second armatures and serves as a link to connect them.

6. The combination of claim 3, in which the rst-named latch member isconnected to said second armatures and serves as a link to connect them.

7. The combination of claim 3, in which the armatures are pivotallymounted on the nonmagnetic support.

8. In combination, a non-conducting member, an electrical contactmounted on the member, a non-magnetic support mounted on the member, apair of electromagnets, means to secure each electromagnet to thesupport, an armature for each magnet, a second armature for each magnet,an electrical contact mounted on each said second armature and movablethereby into cngagement with the first-named electrical contact, a latchmember supported by both of the second armatures, and another latchmember on each rst-named armature and cooperable with the first-namedlatch member.

9. The combination of claim 8, in which the flux path for the secondarmature includes at least a portion of the rst armature.

10. The combination of claim 9, in which the rst-named latch member isconnected to said second armatures and serves as a link to connect them.

11. The combination of claim 8, in which the first-named latch member isconnected to said second armatures and serves as a link to connect them.

JAMES W. WOOLF.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 938,588 Keely Nov. 2, 19091,186,561 Evans June 13, 1916 1,819,061 Bancroft Aug. 18, 1931 1,971,199Owens Aug. 21, 1934 2,097,335 Memmel Oct. 26, 193'7 2,295,881 WheelcockSept. 15, 1942 2,423,116 Price July 1, 1947 2,441,633 Horman May 18,1948 FOREIGN PATENTS Number Country Date 83,895 Austria May 10, 1921

